I recently purchased a Knox brand electric cooler (48 watts) than can run on a 12V DC power cable in our PHEV. I haven't used the cooler yet, but I did have a question about using it in the car when it's parked while shopping. I'm assuming I can power the cooler when parked, but my concern is will the PHEV's battery management system be up to the task. If I only had one car battery I wouldn't even think about it, but given the PHEV has a huge battery that feeds the smaller battery shouldn't there be sufficient battery power for short periods of time like an hour or two? I don't want to risk harming either of the PHEV's batteries if powering the cooler when parked is going to do that.